Thread embedding method (also known as polymer molding method) is to directly embed suture (or polymer suture) between skin and meibomian through suture, so that the upper eyelid skin and meibomian adhere to form double eyelids. This method is simple to operate, with little trauma, no scar, rapid swelling reduction and no need to remove stitches. More suitable for young people, with thin eyelids, long eyes and no loose skin. Not suitable for people with thick eyelids, loose skin and older age, double eyelids may disappear. 2. Double eyelid incision is a permanent double eyelid operation, which removes slack skin, orbicularis oculi muscle and fat by incision, and directly sutures the skin with orbicularis oculi muscle or levator palpebrae aponeurosis under direct vision to form double eyelid. This method needs to cut the skin, which is slightly traumatic, but the upper eyelid structure can be adjusted through the incision, and the effect is reliable and lasting, which is suitable for single eyelid in various situations. The swelling time is a little longer, and the wound will leave a linear scar.